The Ancient Key
by Tsukisamu Sayako
Summary: X-over with FF7. When Naminé told him that he would be asleep while she's repairing his memories, Sora never thought that he would instead be sent to another world to save that world as well. Slight AU Sora/Naminé, Kairi/Sora, Roxas/Kairi
1. The Dream Like No Other

**Chapter 1 – The Dream Like No Other**

* * *

The last thing Sora remembered after stepping into the white flower-shaped pod was the tender smile on Naminé's face. As the petals enclosed him in darkness, the Keyblade Master could only smile and trust in Naminé's abilities to restore his memories to him.

"Thank you, Naminé," he said softly before succumbing to the urge to sleep. The last thing he saw were thin lines of green cutting through the black darkness as a soft humming of machinery surrounded his hearing.

* * *

_What are you dreaming about, little one?_

Sora opened his blue eyes and looked about the darkness that surrounded him.

_Do you dream about worlds you visited?_

"Who's there?" he called out, looking about him with confusion. Wasn't he supposed to be asleep?

_Do you dream about worlds you never found?_

"Worlds I never found…" he said softly, wondering what it meant.

_Do you dream of an adventure that you never experienced?_

"An adventure…" he gasped as a bright light engulfed him.

_Will you believe in dreams or in reality?_

* * *

"Sora, wake up," a deep tenor voice entered into his consciousness. Sora groaned and opened his eyes to see himself seated in a rather decrepit train that was speeding to an unknown location. He stretched out his limbs and looked up with confusion. The face that hovered over him was strangely familiar but he couldn't recall the name.

"Who?" he questioned.

"I'm Cloud, remember? Is there something wrong?" the blond-haired man replied curiously. "This is no time to be sleeping on the job, Sora," he added sternly.

"We're almost there," came a lilting soprano voice. The two turned their attention to the girl that peeked into the train car where they occupied and Sora blinked with confusion.

"Okay, Olette," responded Cloud tersely. "Get Hayner and Pence ready. We move immediately upon arrival."

"Yes, sir." The brown-haired girl then disappeared out of the open doorway.

Sora took a tentative look out the window of the train and frowned at the sight of dark buildings. The place reeked of pollution and he could even smell it in the air. He wrinkled his nose at the unpleasant smoggy smell.

Cloud chuckled. "Get used to it," he said. "The smell will linger until we disable all the reactors."

"So what's our job tonight?" Sora questioned, drawing his attention back to the man next to him. As he asked the question, the two could feel the train slowing down until it stopped with a lurch.

"I'll fill you in on the way," said Cloud. "Let's go." The spiky-haired man then jumped out of the train car to deal with the initial guards that surrounded the train.

"Sora, let's go!" he shouted, jolting the Keyblade Master from his reverie. He landed softly onto the platform and stood up to see Cloud at the end of the platform next to a doorway leading to the left. "This way!"

"Coming!" he shouted and began running toward the doorway. However, before he reached there, two blue-uniformed MPs appeared from behind the train engine and rushed toward him. The brown-haired teen quickly skidded to a halt and prepared for battle.

"Eh!?" he exclaimed as he clutched at the Kingdom Key that did not appear in his hand. A metallic sound directed his attention onto his back and he pulled the familiar blade in preparation for battle. He dodged as the first of the two MPs shot at him and jumped up. He brought the blade down and grimaced to hear a loud thump as the metal hit the skull of the unfortunate man. The man quickly went down with a thud. Not stopping in his assault, Sora quickly swung the Keyblade horizontally. The blade caught the back of the other MP's head and the second guard quickly joined the first on the ground.

Sora made a face at the sight before turning his attention back to the way Cloud went. Without another word, he continued his way to their target.

When he passed through the doorway, he found himself standing on a main road leading to a glowing structure in the distance. A tall slim teen with honey blonde hair stood in the shadows, beckoning him. Sora nodded silently and ran towards the teen who began running down the road leading to the left. The brown-haired teen stilled upon seeing the multitude of neon lights and the grotesque smell of sewage that permeated the air.

"Ugh," he grimaced.

"Don't stop," came a soprano voice. "If you stop, the smell gets worse. Come on!" Sora sighed and followed the brown-haired girl named Olette to their destination.

Soon, they stopped in front of a metal gate leading to the glowing structure that he saw before. Sora noted with a smile that the smell of pollution seemed less overwhelming there. A chubby teen was kneeling in front of a panel fiddling with the circuits.

"Shinra keeps the air around their beloved reactors cleaner with circulating air," answered Olette upon noticing Sora's sniffing of the air.

"I see. I'm Sora," he said.

"I'm Olette," replied the girl. "Nice to meet you."

"Hayner," said the thin boy.

"Pence," said the chubby boy that was tinkering with the circuits. "Is it true? That you were once a SOLDIER?"

"Uhhh…" said Sora, scratching his head. "What's SOLDIER?"

"Man, where have you been!? SOLDIER is the elite rank of military personnel in Shinra. _Everyone_ knows about them!" exclaimed Hayner.

"Sora's a bit young to have been in SOLDIER, guys," said Olette. "He's not older than any of us! Besides, I don't think he'd be wearing all white if he was part of SOLDIER."

"I thought I told you guys to keep it down," said Cloud as he walked up to them, his Buster Sword drawn and ready to spill some Shinra blood.

"Sorry, Cloud," said Pence. He finished his tinkering of the circuits and replaced the panel. He then pressed a button on the wall next to the gate and the gate slid open effortlessly.

"You guys go on ahead and set up the explosions. Sora and I will set up the main charge," Cloud commanded.

"Aye, aye, Sir!" saluted the three with grins on their faces and went up ahead.

"So what are we doing here?" asked Sora as they began their way to the reactor.

"We're here to destroy that thing," said Cloud grimly, pointing at the reactor. "Shinra Company has been sucking the life out the planet and if we don't stop their reactors, no one would be able to live on Gaia ever again."

Sora frowned. "Is there no government to stop them?"

Cloud laughed mirthlessly. "Government? Shinra _is_ the government. I guess Kairi was right when she said you came from a different planet."

Sora blinked with curiosity. The name Kairi was familiar to him, but he couldn't recall for the life of him where he had heard it.

"What did she mean by that?" asked Sora uncertainly.

"She'll explain once we get back to the Seventh Heaven. Let's just focus on our job." They entered an elevator and Cloud set the transport to take them to the highest floor.

"You've been in a reactor before?" Cloud nodded with a slight frown.

"I worked for Shinra before," he replied, a scowl becoming apparent on his face.

"What happened?" inquired Sora. Cloud remained silent and soon the elevator came to a stop. The door slid open and the pair quickly made their way to the entrance of the reactor. Cloud muttered a soft curse when a group of four MPs appeared in front of them upon the opening of the metal doors.

"Halt!" shouted one of the MPs. The two swordsmen drew forth their weapons and prepared for battle.

Cloud used his broadsword to shield himself from the bullets while Sora sidestepped the shots in a dance-like manner. Once the guards had stopped shooting at them, Cloud quickly jumped up and did a forward somersault before slamming his blade onto the ground to split the ground into three with streams of fire. The three fire lines hit three of the four enemies and slammed them against the walls behind them, knocking them out instantly.

The last man had no fortunate fate waiting for him as Sora lunged at him with his Kingdom Key and slashed across the torso of the hapless guard in quick succession. A sickening crack was audible as the man's clavicles were broken.

Sora grinned in triumph and flicked his thumb across his nose with a sniff. He turned to look at the older man, who had a smirk on his face. The two then entered into the reactor and made their way across the catwalks, down links of chain, across pipes, and down ladders until they landed upon a long stretch of metal grating that stood between them and a pool of glowing green liquid.

Sora gulped with apprehension as they began their way across the catwalk, hoping that the rusty looking metal grating would not buckle under their weight.

They stopped halfway across the bridge, scowling at the appearance of a Sweeper and two Grunts.

"What I wouldn't do for a Bolt Materia right now," scowled Cloud as he held the Buster Sword tightly in his two hands.

"Bolt? That thing is weak against lightning?" asked Sora, a small grin appearing on his face.

Cloud nodded and quickly maneuvered his sword to block the incoming bullets.

"Well then, that'd be easy." Sora mentally reached into his arsenal of magic and raised his Keyblade, pointing it upward as he shouted, "Thunder!" Instantly, a bolt of lightning appeared at the tip of the Kingdom Key and arced toward the machine.

The Sweeper shuddered under the attack and soon fell into pieces, smoke rising from the debris. The two Grunts, in retaliation, shot at Sora, who barely managed to escape death with a scratch to his arm.

"Ow," he winced, bringing his free hand up to staunch the flow of blood. Cloud scowled and attacked the two Grunts, decapitating one and slicing diagonally across another to deal a fatal blow. The two Grunts fell unceremoniously onto the metal grating, blood seeping through the catwalk and dripping down to the pool of eerie liquid below.

Sora watched as Cloud kicked the bodies off the catwalk and down into the pool of liquid, two faint splashes could be heard as the bodies hit the surface.

"What _is_ that thing down there?" asked Sora with a gulp.

"It's Mako," replied Cloud, picking up a green sphere towards the end of the catwalk leading to a wider platform. Sora walked up to the taller man and looked at the sphere with interest.

"This is a Restore Materia," said Cloud, inserting the sphere into one of the two slots that were in his Buster Sword.

"How do you know that it's a Restore Materia?" asked Sora.

"I just know," grinned Cloud. He turned to face the main control and pulled out a small detonation packet from a satchel that he was carrying the entire time.

"Cover me for a moment," he said to Sora.

"Yes, sir!" saluted Sora as he scanned the vicinity for any enemies. He noted that for an enemy territory, there did not seem to be a lot of guards patrolling. A series of beeps drew his attention back to Cloud and he watched as a timer of ten minutes began to count down.

"Mission accomplished," said Cloud with a smirk. "Now let's get out of here."

The two turned to leave but found themselves nearly falling onto the catwalk with a sudden quake. A giant machine now stood between them and the exit, its scorpion tail raised for an attack.

"Guard Scorpion," spat Cloud. "I should've expected this."

"We'll just have to beat it," responded Sora as he dashed forward and brought his Keyblade down on the metal plating. A loud clink could be heard as metal hit metal but to Sora's dismay, his attack didn't do so much as a dent on the plating. The Scorpion retaliated by lashing out with its metallic tail, throwing the still airborne teen into the piping behind him.

Sora grunted with pain and saw stars as the back of his head hit the metal plating. Although his back ached from the impact and a nasty gash was on his stomach, Sora knew that he could still battle. He stood up and pointed his Keyblade up with both of his hands on the hilt. "Cure!" Instantly, his wounds were healed. The pain still lingered, but at least he could move better now.

In the mean time, Cloud was dealing damage to the machine with his sharp sword, making cuts into the metal plating as well as slowly severing the joints of the machine's legs. He quickly jumped back upon seeing the Scorpion's tail coming down on where he stood.

"Thunder!" shouted Sora as the Scorpion prepared to attack. Smoke rose from parts of the Scorpion, but it was not out of commission. It raised its tail higher and pointed the tip of the tail towards the two fighters.

"Watch it," said Cloud. "It'll counter with a laser attack if we attack it."

"Even with Thunder?" asked Sora.

"Even with Thunder," replied Cloud. "Just wait."

Sora frowned; he was not one for waiting around in a battle. But still, he waited with Cloud and after several tortuous moments, the machine finally pulled its tail back.

"Go!" shouted Cloud as he jumped up and brought his blade down on the top of the machine's head. The hard armor deflected the strike and Cloud quickly turned his blade to block the bullets that zoomed toward him.

"Cloud, watch out!" screamed Sora as the tip of the tail lit up with red. A red beam of laser shot out and caught the blond-haired man on his back, burning through the black woolen vest with ease and scorching the pale skin. Fortunately, Cloud had maneuvered enough that the attack was not fatal. He landed on his feet on the catwalk and stood up tenderly with a visible wince.

"Thunder!" the brown-haired teen shouted again, letting another bolt of lightning land effortlessly on the machine. Cloud then followed up with the Braver attack that cut through the metal plating. The robotic boss shuddered under the combined attacks as electricity sparked across the wounds of the robot. The two men shielded their eyes as the machine exploded in front of them.

Cloud looked at the timer and frowned. "Six minutes left, let's get out of here!"

Sora nodded. Without another word, the two men quickly ran back they way they came and helped Olette up when they found her with her foot stuck in a narrow break between the metallic plates leading out of the reactor.

"Your foot's alright?" asked Sora as he inspected the slightly swollen foot.

"I'll live," she replied with a weak smile. She limped slightly as she ran, but Cloud didn't seem worried about it, so Sora didn't bother pursuing the subject matter further.

The three quickly made their way out the main reactor. However, they stopped in at the top of the stairs when they saw a battalion of MPs coming towards them.

"Oh, give me a break!" said the brown-haired boy exasperatedly as he pulled out his Keyblade in preparation for battle.

"Leave it to me," grinned Olette as she pulled out several hand-held explosives from her sleeve. A smirk appeared on her face as she threw the bombs at the incoming battalion. "Fire in the hole!" she shouted as the three dropped to the ground. The bombs exploded upon impact and screams of terror filled the air.

Slowly, the three "terrorists" stood back up and Olette sounded a nervous chuckle at her handiwork. A decent gap now stood between them and the rest of the stairs.

"Good job, Olette," said Cloud exasperatedly. He then ran and jumped across the gap with practiced ease. He then turned and watched the girl carefully as she too jumped across the gap. Olette landed into Cloud's supporting arms as she nearly stumbled over her landing. Sora grinned and jumped with a running start, spinning like a ballerina in midair before gliding a short distance through the air. He landed softly further down the stairs.

The three then quickly made their way down the stairs and into the elevator, each fidgeting in their own ways as they waited for the elevator to make its descent to the ground floor. After a long tortuous wait, the elevator finally stopped at the ground floor and they hurried out of the deathtrap and made their way out of the reactor facility. As they passed through the gate, the reactor exploded into red fire behind them. Sora took a look back and smiled weakly at their work, wondering if it was worth it.

He knew, of course, that he was in for a big adventure upon waking in this strange world.

* * *

_Disclaimer: Both Final Fantasy VII and Kingdom Hearts do not belong to me. If I did… well, this wouldn't be a fanfic then would it? Haha._

_A/N: So the idea came to me while I was starting another playthrough of FFVII. And out of sheer insanity, I decided to rename the characters with KH names. Don't ask me what name I'd give to RedXIII and Cait Sith, I haven't gotten that far yet. I probably will play through the game as I write this fanfic. Haha. If you have any thoughts on who should be who, feel free to drop a review._


	2. Familiar Faces, Different Fates

**Chapter 2 – Familiar Faces, Different Fates**

* * *

The five members of the group AVALANCHE sat around in an abandoned house listening to the radio for news on their latest work.

"The Mako Reactor 1 of Midgar was bombed earlier this evening," the radio crackled with sound. "Shinra Company has released information that it was a terrorist act meant to strike fear into the law-abiding citizens of Midgar. No group has yet claimed responsibility for the-". The radio was quickly turned off upon confirmation.

"Well done, everyone," said the leader of the motley crew. Hayner and Pence threw each other high-fives while Sora cheered.

"Alright, we're gonna split up and meet back at the Heaven in an hour. Don't dawdle at Wall Market," he looked at Pence and Hayner, "or at Naminé's Church," he looked at Olette. I don't want to worry about you squirts anymore than I have to tonight." He gave them a smirk.

"Yes sir," replied the three teens unenthusiastically before making their way out of the building. The blond-haired man turned to Sora and tousled the younger teen's hair, much to Sora's annoyance.

"I guess you're stuck with me," he said with a grin. "Unless you'd like to get lost."

Sora made a face that made Cloud laugh. "No thanks," he replied. "I think I'll stick with you."

The two then left the building and made their way into a plaza, where pandemonium reigned as people ran past each other in panic.

The only person who didn't seem affected by the panic was a blond-haired girl wearing a grayish white dress carrying a flower basket in one hand and a sketch book in the other. Her calmness and pale complexion was a stark contrast to the smoggy blackness that was Midgar. A man bumped into her and she nearly fell over if it wasn't for the timely arrival of Cloud and Sora.

"Oof," she said. "Oh, thank you." She turned around and bowed in thanks. When she stood back up, Sora goggled at the familiar face with shock.

"Naminé?" he asked. The blond-haired girl looked at him oddly.

"Do I know you?" she asked.

"Uh, no. Sorry, you just looked like someone I knew," he said sheepishly.

"You better head on home," Cloud said. "It isn't safe here."

"Of course," she smiled peacefully. She then pulled out a yellow lily from her basket. "Here, a flower for your trouble."

"It was no trouble," said Sora, a slight frown on his face.

"It was nice to meet you." The blond-haired girl then left the two men to themselves as she made her way back home.

The blond-haired man turned his attention to the younger lad. "You know her from somewhere?"

"You wouldn't believe even if I told you," Sora said.

"Hmm, guess it'll be a long story. Tell me about it sometimes later. Let's just concentrate on getting back to Sector Seven."

"Sector Seven?" Sora asked as he scratched his head.

"It's where my friend's Tifa's restaurant is located," replied Cloud. "You remember where it is, don't you?"

Sora scratched his head and shook his head nervously.

"Hmm," hummed the blond-haired man out loud. "Something must've happened when you fell asleep on that train."

"Tell me about it," grumbled Sora. The pair had walked onto an empty cobblestone street overlooking the train tracks. In the direction they were heading were two Shinra MPs.

"Uh oh," said Sora. The pair turned around to try to look inconspicuous, but it was too late.

"Hey, you two, stop right there!" shouted one of the MPs. The two members of AVALANCHE disregarded the command and began running back the way they came, but in their way were three MPs.

"Halt!" commanded yet another MP.

"This way," said Cloud as they turned to their right down another street. Unfortunately for them, another patrol of MPs stood in their way. The two men soon found themselves cornered on the empty street.

"Oh, give me a break," growled Sora. The ground underneath them began to shake and they could hear a train approaching.

"Well, we'd love to stay and chat," said Cloud with a grin as he neared the edge of the street overlooking the tunnel. Sora grinned as well, following Cloud's lead.

"But we've got a train to catch," he ended for Cloud. Without another moment to spare, the two jumped onto the train and waved farewell to the furious MPs, who were trying to shoot at them as they sped away.

"Hey!" shouted Sora. "That's not very nice!" He then proceeded to blow a raspberry at the blue-uniformed men, even though he was sure that they wouldn't be able to see it.

Cloud laughed heartedly. "Come on. Let's get inside before someone else sees us."

The two men then opened up the hatch door on top of one of the train carts and jumped in, surprising the other AVALANCE members who were also aboard the train.

"Where have you guys been!?" asked Olette incredulously. "We were getting worried!"

The blond-haired man grinned haughtily and sat down on one of the crates within the train car. Sora sat down on the dirty ground in a plop and leaned against the metal wall to relax. He watched as Olette approached him with a handkerchief.

"Kairi forgot to give this to you before you left," she said. "Your face is kind of dirty." She chuckled softly. Sora blushed slightly and scratched the back of his head.

"Oh, thanks," he replied, accepting the handkerchief. He wiped his grimy face and refolded the soft handkerchief, placing it in one of the pockets of his red baggy shorts.

"Let's head back to the passenger cars before someone on the train decides to check up on the cargo cars," suggested Pence. "I heard the conductors have been really edgy since the breaking news report."

"Yeah, we don't want to get caught, would we now?" said Hayner with a grin. He then made his way through the boxes and opened the sliding door that led to the passenger car. He looked into the window at the occupants of the car to search for any Shinra conductors.

"The coast is clear," he said as he waved at them. The group of miscreants then made their way into the almost empty passenger car and sat down. Pence had made his way to a computer console at the opposite end of the car and had started tinkering with it. Olette stood next to him, watching him work on the console then looked up at Sora.

"Sora, come look at this," she said. The Keyblade master made his way over to the two AVALANCHE members. He looked upon the black computer screen and saw a series of dots and lines that resembled a three dimensional blueprint of some sort.

"What's this?" he asked, looking upon the screen with confusion.

"It's the structural blueprint of Midgar," answered Pence. "See the blue flashing dot? That's us traveling on the railways that lead to the station at Sector Eight."

"And we just came from here," said Olette as she pointed at a green looking structure towards the top of the screen. "And these," she pointed at various red flashing dots on the screen, "are security check points Shinra had installed to catch criminals like us," she whispered with a grin.

"Speaking of which," said Cloud as red light flashed through the train car. An alarm siren shrilled as the train passed by the security checkpoint. After some ten seconds, the light stopped flashing and the alarm fell silent.

"Man, I can't wait to get back to the Heaven," said Hayner as he threw his dirty-blond haired head back, slumping on the seat. "I'm starving!"

"I thought that was Pence's line," replied Olette with a giggle.

"Hey, I resent that!" said the chubby teen with a huff. Sora could only grin at the scene.

Soon, the train slowed to a stop at Sector Eight station.

"Last stop of the night," the conductor shouted over the loudspeaker. "This is the last stop of the night, Sector Eight station."

"C'mon," said Cloud as they stepped off of the train. Sora looked about him at the decrepit platform and saw a few wives and friends greeting their loved ones happily with hugs and kisses. Yet, despite the heartwarming scenes, he noticed a severe lack of people out at the time of day. Undoubtedly it was because of the time of the day; after all, it had been night when they started their mission.

The group slowly made their way through the slums to Sector Seven. Sora was disheartened at the sight of the rundown buildings made of metal sheets without proper windows and doors. The only building that was even remotely decent was a rather lively place with a neon sign over the swinging doors that said "Seventh Heaven". Faint music, chatter, and laughter could be heard from the bar, but that was not meant to last for long.

Sora made his way toward the makeshift headquarters of AVALANCHE and watched as Hayner, Pence, and Olette quickly ran into the bar. Cloud entered through the swinging doors shortly after and soon after that, a throng of drunken men and women exited the bar cheerfully. In a blinded window, Sora could see a red-haired girl turning the sign from open to closed.

The brown-haired boy entered the small homey bar and saw Cloud conversing with a black-haired woman wearing a white tank top and a pair of black shorts. Her left foot was in a cast and was propped up on a small wooden stool next to the only dining table in the room. The three other teens who were at the mission were already helping themselves to the meager food that had been laid out on the dining table. The red-haired girl that he had seen earlier was behind the bar drying a shot glass.

"Sora!" she exclaimed upon seeing him. She was about to put down her work when the black-haired woman shook her head.

"Kairi, finish the cleaning. Then spend time with your boyfriend," she teased.

Kairi blushed a deep crimson red and sputtered, "He-he's not my boyfriend!"

Tifa grinned mischievously while Cloud snorted humorously. Sora's own face was slightly tinted with red. The fragile flower was left forgotten in his hand as he tried to hide his embarrassment.

"How was the mission?" asked Tifa quietly.

"It went well," replied Cloud, equally quietly.

"We saw on the news," said Kairi as she finished wiping down the countertop. "Shinra's making a statement in half an hour."

"Good," replied the blond-haired man. "I'll be downstairs."

"I'll go with you," said Tifa as she hesitantly stood up, only to stumble into Cloud's arms when her sprained foot couldn't hold the weight. Both Olette and Kairi giggled softly as their surrogate older sister blushed with embarrassment.

"Don't strain yourself, Tifa," said Cloud.

"Sorry," she replied softly. The blond-haired man then helped Tifa over to a metal platform and the makeshift elevator carried them down to the basement. Hayner, Pence, and Olette finished their meals shortly after and leaped down into the basement to join Cloud and Tifa. Sora had no doubt that it was for the next mission.

The squeak of a faucet turning off caught Sora's attention and he looked back upon the red-haired girl that seemed so familiar yet so unknown to him. She stepped from behind the counter and smiled at him. The brown-haired teen noted for the first time that she wore a white tank top bordered with lavender complemented with a lavender miniskirt. The entire outfit was completed with a purple choker, a pair of purple armbands, and a pair of yellow wristbands. He reddened upon realization that he was staring at the girl.

Kairi giggled softly at her friend's behavior and gasped when she saw a yellow flower in Sora's hand.

"Sora, is that a flower?" she asked hesitantly.

"Huh?" the boy replied lamely and then looked down at the forgotten flower. "Oh! Yes, it's a flower." He scratched the back of his head with his free hand nervously and held the flower out to Kairi.

"For me?"

Sora nodded with a smile and watched as Kairi's gentle hands took the fragile flower from him. She smiled happily back at him and his smile only grew wider.

"Thank you, Sora."

"You're welcome, Kairi." An awkward silence fell over the two as Sora watched Kairi look at the flower.

"You better get downstairs," Kairi said softly.

"A-ah…" replied Sora. Without another word, the brown-haired teen jumped down into the basement, leaving Kairi to her thoughts.

* * *

_Disclaimer: Both Final Fantasy VII and Kingdom Hearts do not belong to me. If I did… well, this wouldn't be a fanfic then would it? Haha._


End file.
